1. Field
The invention lies in the field of image acquisition and specifically in particular combined optical and nuclear image acquisition, and relates to a device for such image acquisition.
2. Description of Related Art
Nuclear imaging methods have proved extremely useful in various fields, in particular in nuclear medical fields and in the search for radioactively contaminated material such as nuclear waste. In nuclear imaging methods the nuclear radiation coming from a spatial region is visualized in a two- or three-dimensional image and thus made perceptible for humans. The spatial region in which the spatial distribution of the nuclear radiation can be sufficiently reliably detected is also designated as nuclear field of view. In cases in which the boundaries of this spatial region are fluid, the nuclear field of view can be defined appropriately, for example, by a predefined sensitivity threshold for the radiation intensity and/or for the spatial resolution of the detector: the nuclear field of view is then the spatial region whose radiation can be detected by the detector having a sensitivity exceeding the sensitivity threshold.
Despite their appreciable benefit, the evaluation of the generated nuclear images is difficult. This is also because the structures identifiable in the nuclear image cannot easily be assigned to the structures perceptible with the naked eye. Thus, for example no anatomical structures are visible in a typical medical nuclear image.
This problem can be ameliorated by applying radioactive markers to known anatomical positions. The markers can then be detected in the nuclear image in order to obtain at least coarse reference points. Systems for hybrid SPECT/CT or PET/CT recording are known in order to superpose CT images containing anatomical information with nuclear images. At the present time, methods are also being developed to represent three-dimensional nuclear images in suitable perspective and superpose with a video image in order to jointly detect anatomical and nuclear image information in this way.
Apparatus for the combined detection of x-ray and optical images are also known, possibly from DE 10049103, JP 61057804, US 2007/0019787, U.S. Pat. Nos. 6,447,163 and 3,679,901. However, the approaches used there cannot easily be applied to the visualization of nuclear radiation since the x-ray and nuclear imaging methods are based on different basic principles. In US 2007/0019787, the x-ray and optical images must additionally be recorded in a time-offset manner. Moving samples cannot therefore be optimally detected.
EP 0 743 538 describes a device for the remote localization of radioactive sources in an observation zone. The apparatus has a mirror and an optical camera for supplying an image of the observation zone and means for detecting radioactive rays. The means for detecting radioactive rays comprises a collimator having a single collimator opening (pinhole collimator) which allows the recording of a spatially resolved nuclear images. The nuclear image can then be combined with the image of the optical camera, However, the attainable image quality of the nuclear image is restricted by the pinhole collimator in a certain time frame.